Was doing a search of the photo data base and stumbled across an interesting photo... What grabbed my attention was the fact the tug is underneath the B777 towing the aircraft...?
Is this a common practice in LHR while towing aircraft...?

I don't believe it is possible to attach a towbar to the landing gear from the back. My guesses are either:

A) a tow bar is sitting on the ramp and the tug is not attached to it.
B) the tug and towbar are connected to each other but not to the aircraft. The tug is repositioning to hook up to the 777 or perhaps going somewhere else.

I would guess that it is in this position because it is actually pushing the aircraft forward rather than backwards. I think that the so-called "tugs" don't actually tug, but push and so it couldn't pull the aircraft along behind it. Perhaps it needs to move from the maintenance area to the gate and doing it this way saves wasting a lot of fuel by starting the engines and taxiing.

Most large aircraft have tow bar connections on both sides of the nose gear for this purpose. Used in this case because the aircraft is a tight fit in the hanger and tug would have no space in front of the aircraft once it was inside and would need to get out. Some hangers have tug size doors to let the tug through the nose end when the aircraft is in. Manoeuvring aircraft in and out of hangars is precision and is a responsible skill.

There is a time-lapsed video online of an AA 777 having an engine change. It shows the tug first towing the aircraft into the hangar and then being positioned as shown in this picture to push it further into the hangar. Sorry, I don't have a link to the video. It's quite interesting to watch though.

Quoting m1m2 (Reply 11):There is a time-lapsed video online of an AA 777 having an engine change. It shows the tug first towing the aircraft into the hangar and then being positioned as shown in this picture to push it further into the hangar. Sorry, I don't have a link to the video. It's quite interesting to watch though.

On a side note, I realized that in CDG, I realized that narrow body planes are pushed back with a remotely controlled "tractor" which is attached to one wheel of the main landing gear:http://www.youtube.com/watch?v=67G1A-Wsov0

Why is that, and also: are there other airports doing that? Never saw this before.
Interestingly, once the plane is pushed back, and the "tractor" detached, the actual human sits on the device and drives it back, instead of remotely controlling it.